The formation of disulfide bonds is an attractive strategy for binding together and stabilizing macromolecular structures. This is in part due to the ease in which disulfide bonds can be formed: by the heating of compounds with elemental sulfur, through the oxidation of free thiols (often by only ambient oxygen), or through the ring-opening of a cyclic disulfide. The sulfur-sulfur bonds formed through these methods are reasonably stable for further processing and chemical transformations, but they can be selectively cleaved by light or heat, allowing for network rearrangement, and this has been exploited in the preparation of self-healing materials. Perhaps the most broadly applied condition for the degradation of disulfide bonds is the use of reducing conditions, which has been utilized for intracellular drug delivery by relying on the relatively high concentration of glutathione within cells.
A need exists for new and improved compositions and methods relating to the formation of disulfide bonds in, e.g., macromolecular architectures.